Pressure carburetors



g- 1965 A. L. MENNESSON 3,198,498

PRESSURE CARBURETORS Filed July 2, 1962 3 Sheets-Sheet 1 {NVENTUR 6 ,xs w/ m will ATTORNEYS Aug. 3, 1965 A. MENNESSON PRESSURE GARBU'RETORS 3 Sheets-Sheet 2- Filed July 2, 1962 N VE N TOR AA/Jr/F Low: MFA/mama ATTORNE S 3, 1965 A. MENNESSON 3,198,498

PRESSURE CARBURETORS Filed July 2, 1962 3 Sheets-Sheet 3 INVENTOR g zlaAay z mma/vars i United States Patent 3,198,498 PRESSURE CARBURETOES Andr Louis Mennesson, Ncuilly-sur-Scine, France, assignor to Socicte Industrielle de Brevets et dEtudes S.I.B.E., Neuiliy-sur-Seine, France, a society of France Filed July 2, 1962, Ser'. No. 206,581 Claims priority, application France, Oct. 9, 1961, 875,431; Jan. 16, 1962, 884,994; Mar. 9, 1962, 890,618 14 (Zlaims. (Cl. 261144) The present invention relates to pressure carburetors, that is to say carburetors of the type wherein, at least for some conditions of operation of the engine fed by the carburetor, fuel is injected under pressure by a pump into the engine feed pipe.

In carburetors of this type, fuel is usually metered by the pump itself in accordance with the value of some factors such as the suction, the number of revolutions per minute of the engine, the temperature, and so on. Other carburetors make use of means located downstream of the pump and capable of by-passing a variable portion of the output of said pump. Both of these solutions are relatively expensive because they require a very accurate construction of the pump and of the metering means and a very delicate preliminary adjustment. Furthermore, such carburetors are liable to get out of order. Generally speaking the cost and maintenance of such carburetors is very high.

The object of the present invention is to provide a pressure carburetor which is better adapted to meet the requirements of practice than those known up to this time, and in particular which is cheaper to manufacture and more reliable in operation.

The pressure carburetor according to the present invention is characterized in that it comprises a chamber in which is collected fuel'previously metered by its flow through a passage of variable cross section area proportional to the variable cross section area of the air inlet of a given portion of the air feed pipe, the fuel from this chamber being injected under pressure into said air feed pipe downstream of said portion thereof by means of a pump the suction of which is connected with said chamber, the difference of pressure under which fuel is driven through the above mentioned passage of variable cross section area being equal to the difference of pressure between the upstream and downstream sides of said air inlet.

Preferred embodiments of the present invention will be hereinafter described with reference to the accompanying drawings, given merely by way of example and in which:

FIG. 1 is a diagrammatic vertical sectional view of a carburetor made according to an embodiment of the present invention;

FIG. 2 and 3 are view-s similar to FIG. 1 but relating to modifications, respectively;

FIG. 4 is a diagrammatic vertical sectional view of another embodiment of the invention;

FIG. 5 shows a modification of a detail of the carburetor of FIG. 4;

FIG. 6 is a view similar to FIG. 4 and showing still another embodiment of the invention;

FIG. 7 shows a modification of a detail of the carburetor of FIG. 6.

The pressure carburetors shown by the drawings (FIGS. 1-3) comprise an air feed pipe '1 leading to the engine and into which opens a fuel injection orifice 2 fed from a fuel pump 3, the air feed pipe 1 comprising a portion 1a limited at its downstream end by the usual throttle valve 7 and at its upstream end by throttling means 8 (FIG. 1), 9 (FIG. 2) or 10 (FIG. 3) automatically controlled so that the pressure in air pipe portion 1a is substantially constant, or varies according to a pre- 3,198,498 Patented Aug. 3, 1965 "ice determined law as a function of the air flow rate through pipe 1.

Pump 3 performs no fuel metering function but serves merely to supply the necessary injection pressure. The suction of this pump 3 is connected, through a conduit 4 with a chamber 5 fed with fuel which has been metered by being made to flow through a passage 6 the cross section area of which is constantly kept proportional to that of the upstream end of air pipe portion 1a, the fuel flow through this passage 6 being produced by a pressure difference equal to that existing between the upstream and downstream sides, respectively, of the above mentioned throttling means 8 (FIG. 1), 9 (FIG. 2) or 10 (FIG. 3), chamber 5 being constantly kept at a pressure equal to that existing in air pipe portion 1a.

Thus, throttling means 8 (FIG. 1), 9 ('FIG. 2) or 10 (FIG. 3) must be operatively connected with the means for varying the cross section area of passage 6, which is located between a constant level chamber 11 and chamber 5. Constant level chamber 11 is connected through a passage 12 with the air intake '13 of air pipe 1 (or with the atmosphere) and chamber 5 communicates through an orifice or passage 14 with the portion 1a of air pipe 1 The air intake 13 may be connected with a filter or suction damper. V

In the construction illustrated by FIG. 1, the throttling means 8 consists of a cylindrical member of a diameter at least equal to that of airpipe 1 and which extends through a hole 15 provided'in thewall of pipe portion In. Member 8 is rigid with a piston 16 of a diameter greater thanthat of said member and movable with a sliding fit in a cylinder 17 extending transversely to air pipe 1. This piston 16 is urged outwardly with respect to air pipe 1 by the suction existing in pipe portion 1a and transmitted through a conduit 18. Piston 16 is urged in the opposed direction by a spring =19. The annular volume limited in cylinder 17 by member 8 and the adjoining end face of piston 16 communicates through a conduit 20 with the air intake 13 (or with the atmosphere).

Of course, piston 16 movable in cylinder 17 might be replaced by a diaphragm bellows or the like acting on member 8 under the efiect of the suction existing in pipe portion 1a.

In the construction of FIG. 2 the throttling means consists of a pivoting disc 9 connected to piston 16 through a lever 21 rigid with said disc and a connecting rod interposed between this lever and piston 16.

In the construction of FIG. 3 (and alsointhose of FIGS. 4 and 6) the throttling means consist of a disc 10 eccentrically mounted in the air pipe so that the suction of the engine tends to open this disc against the action of a spring 19a.

As above stated, in any case the cross section area of the air passage at the upstream end of air pipe portion 1a, determined by cylindrical element 8' (FIG. 1) disc 9 (FIG. 2) or disc 10 (FIG. 3), is such that the suction in air pipe portion 1a is substantially constant or varies according to a predetermined law as a function of the air flow rate, this suction depending essentially upon the characteristics of spring 19 or 19a and also possibly upon the eccentricity of the pivot of disc 10 in the case of FIG. 3.

In order to control the cross section area of passage 6 in accordance with the position of the throttling member 8, 9 or 10, said passage 6 is of annular shape, being limited outwardly by the fixed wall of an orifice 23 and inwardly by a moving needle 24 of non-cylindrical, and for instance substantially conical, shape, this needle being moved axially in orifice 23. In the construction of FIGS. 1 and 2 this needle 24 is rigidly connected with cylindrical member 16 through a rod 25. In FIG. 3 the eccentrically mounted disc is connected to needle 24 through a link 26 interposed between said disc and the sliding rod which carries needle 24, said rod 25 being guided in a sleeve 27 so as to ensure a fluidtight passage of the rod through the wall of air pipe 1. In these three constructions, orifice 23 is located in a chamber 28 the upstream portion of which communicates with constant level chamber 11 and the downstream portion of which communicates with chamber 5.

This chamber 5 is of a volume sufficient to reduce to zero the speed of the .fuel stream fed through passage 6 so that said fuel collects by gravity at the bottom of said chamber 5. Obviously, this volume is in relation with the total volume of the engine cylinders to be fed by the carburetor.

In order to keep chamber 5 constantly at the same pressure as pipe portion 111, said chamber 5 communicates with said pipe portion 1a through a passage 14 of a cross section area relatively great with respect to those of the orifices through which fuel is delivered toward the engine. These last mentioned orifices may consist either of the injection orifice 2 itself or of an orifice 29 disposed downstream of the pump, or again of both orifices.

The suction of the pump is connected with the bottom of chamber 5 the shape of which is designed so as quickly to collect the Whole of the metered fuel toward said pump suction. For this purpose, as shown, chamber 5, advantageously has inclined walls 5a.

Means should be provided to prevent the fuel sucked i into chamber 5 from gushing into air pipe 1 through passage 14, for instance due to its momentum acquired when flowing through passage 6. If the rod 25 which carries needle 24 extends through said passage 14 with a substantial play, the means in question may consist, as shown by the FIG. 1, of a shield 30 carried by rod 25 above passage 6. If, on the contrary, as shown by FIG. 3, rod 25 does not extend through passage 14 but is mounted with a pratically fluidtight fit in sleeve 27, it suffices to connect chambers 28 and 5 with each other through a conduit 31 which is not in line with passage 14.

Pump 3 may be driven by the internal combustion engine itself, but preferably it is driven by an electric motor so that its speed does not vary too much. This pump, which has no metering function, may be of any type whatever (for instance, either a centrifugal pump or volumetric pump) and its particular construction is independent of the present invention.

The .injection orifice is advantageously in the vicinity of the inlet 32 of the corresponding cylinder of the engine (FIG. 1), controlled by a valve 33 or any other equivalent means.

In the case of a multicylinder engine having at least one injection orifice 2 for every cylinder, a distributing device is, of course, interposed between pump 3 and the injector. This distributing device may be fixed, as shown at 34 (FIG. 1), thus permanently connecting the delivery of the pump with the respective conduit 35 leading to the injection orifices 2. It may also be a rotary distributor, as shown at 34a in FIG. 3, driven by the engine so as to connect the delivery of the pump successively with each of the conduits 35.

Carburetors according to FIGS. 1 to 3 work as follows:

As above stated throttle member 8, 9 or 10 produces, whatever be the position of throttle valve 7 a substantially constant suction in portion 1a of air pipe 1 (or at least a suction varying according to a predetermined law as a function of the air flow rate).

The fuel flowing through passage 6 is subjected, upstream of this passage 6, to the pressure existing in the constant level chamber 11 (that is to say, owing to the provision of passage 12, to the pressure existing in air pipe 1 upstream of the upstream end of pipe portion 1a) and, downstream of this P g t0 th Pressure BXiSting in chamber 5. This last mentioned pressure is equal to that existing, downstream of the upstream end of pipe portion 1a, owing to the fact that the cross section area of passage 14 is much greater than that of orifices 29 or 2.

Fuel is therefore fed through passage 6 under a pressure difference equal to that existing between the air in take 13 and the air pipe portion 1a.

In view of this, the air flow rate and the fuel flow rate are substantially proportional to each other so that the richness of the air and fuel mixture is practically constant.

The fuel fed through passage 6 collects at the bottom of chamber 5 Le. close to the suction orifice of pump 3. Pump 3 permanently pumps the liquid just collected and delivers it through distributor 34 or 34a to the injection orifice 2. It should be noted that orifice 29, when it exists, must be dimensioned in such manner that, when the flow rate of fuel is'maximum, pump 3 is capable of instantaneously evacuating the fuel passing through orifice 29. But for speeds of rotation of the engine lower than those corresponding to maximum power, the pump delivers not only fuel but also air and supplies conduit 35 and orifice 2 with a mixture of air and fuel.

The invention therefore provides a pressure carburetor which is simple and cheap to manufacture and reliable in operation because it does not include any complicated part and can hardly get out of order.

Although the carburetor according to the present invention makes use, to meter fuel, of the suction existing upstream of themain throttle valve 7, as in the case of conventional carburetors, the present device is free from the defects of, these carburetors, among which are the following ones:

Necessity to provide, in addition to the normal running feed circuit, an idling feed circuit and an accelerating pump;

Risks of icing due to evaporation of the fuel on the wall of air pipe 1 in the proximity of movable elements, which causes the formation of ice, on said movable elements. This is avoided by introducing fuel sufficiently downstream of said movable elements;

Limitation of the power of the engine due to the use of pipes and conduits of respectively small cross section area necessary to keep a suitable speed circulation of the fuel.

In the construction FIGS. 1, 2 and 3, pump 3 is, for instance, of a centrifugal or volumetric type In the construction of FIGS. 4 to 7, which will be hereafter described, the pump is in form of an ejector the propeling gas of which is air fed by an auxiliary pump or compressor 36 preferably driven at constant speed, for instance by an electric motor. This air may be collected through a conduit 37 either from the atmosphere or more advantageously, as'shown by the drawings, from the air intake 13 in order to have the benefit of the filter mounted in said air intake.

In order to constitute the ejector, the delivery conduit 39' of pump 36 is provided at its end with a nozzle 38 opening into the throat of a venturi 40 formed in the corresponding end of conduit 4, which leads from chamber 5, the whole being mounted immediately upstream if injection orifice 2, said nozzle 38 being coaxial with venturi 40.

It will be understood that the air stream ejected through nozzle 38 creates in venturi 40 a suflicient section to draw in the fuel conveyed through conduit 4-from chamber 5, and to discharge it into the air feed pipe 1.

The advantage of this kind of pump results from the following considerations:

A volumetrical or centrifugal pump such as shown at 3 in FIGS. 1, 2, 3 delivers an air and fuel mixture where the fuel to air ratio is variable, the relative amount of air being practically zero at full power and on the means to air feed pipe.

amazes contrary being relatively great at or near idling speed or at low speed running under full load.

If this pump is dimensioned to supply fuel without air under a pressure of 400 g./cm.?, of instance when the power is maximum, it becomes nearly inoperative when the flow rates that are required are much lower.

For instance, when the engine is running at 400 rpm. and at full throttle, since the amount of fuel to be supplied to the engine is about fourteen times smaller than at 5,500 r.p.m.,' the pump will deliver A of the amount it delivers at 5,500 r.p.m. so that the relative amount of air will be much greater and, as a consequence, the pressure supplied by the pump will be low, not higher than some tens of g./cm. This, is duetothe fact that thedelivery pressure of centrifugal or volumetrical pumps decreases consideriably when liquid is replaced by gas. In the 'case of centrifugal pumps the reason is that the pressure they develop depends .upon the specific weight of the fluid passing through the pump and in the case of gear pumps, or blades pumps, the reason is that leaks are unavoidable along the sides of the casing and such leaks take a considerable importance when gas is being compressed instead of liquid. The lack of pressure occuring in these conditions slows down the circulation of fuel between the pump and the injector" and also makes the delivery flow rate dependent upon the difierence of levelb'etween the pump and the injector. As a matter of fact, this diiference of level is of the same-order of magnitude'as the delivery pressure of the pump.

As a consequence of these phenomena, the feed of I fuel isdefectiVe and. causes a slowing down of the flow of fuel from chamber 5 to the injector, thus causing unsatisfactory accelerations and a bad working of the engine.

These drawbacks are avoided by the use of an ejector device which draws liquid from chamber 5 by means of a suction which is always substantial and which, furthermore, has a tendency to be more important when the relative amount of liquid in the mixture is small, which thus ensures a very quick flow of fuel from the metering Furthermore, the air stream issuing from nozzle 33 atomizes the fuel, which is essentially useful. v

Whatever be the type of pump 3, there may be provided means responsive to the suction existing in air feed pipe 1 downstream of throttle valve 7 for placing the above mentioned pump out of action as soon as this suction exceeds (in absolute value) a given limit and back into action, as soon as said suction becomes smaller than said predetermined limit.

According to a first solution, shown in dotted lines in FIG. 4, the'suction pipe of air pump 36, instead of starting from air intake 13, starts from an orifice 41 located downstream of the main throttle valve, this suction pipe being designated by 37a.

. Thus, when throttle valve 7 is in the position corresponding to idling'running (position shown in dotted lines) orifice 41 is subjected to :a considerable suction which is the sameas'that existing at orifice 2. The deliveryrate of air pump 35 then becomes practically zero so that ejectorpump 3 is brought out of action. However, fuel is drawn from chamber 5 to orifice 2 since this last men tioned orifice is subjected to thestrong suction existing in airpipe 1.

According to'a second solution, there is provided, on one of the suction and delivery conduits of air pump 36, preferably on delivery conduit 39, a valve member controlled by a mechanism, advantageously of the diaphragm type, responsive to the suction existing in air pipe 1 downstream of throttle valve 7.

As shown by FIG. 5, this valve member consists of a piston 42 slidable in a cylinder 43 extending across conduit 3 9. This piston 42 is actuated by a diaphragm 44 which forms a movable wall of a chamber 45 connected through a conduit 46 to air pipe 1, a spring 47 urging (3 diaphragm 44 in a direction opposed to that in which acts the suction transmitted through conduit 46. 7

Thus, when the action of said suction overcomes that of spring 47, diaphragm 44 is appliedagainst a finger 48, bringing piston 42 into the position (shown by FIG. 5 where it stops the flow of air from pump 36 to nozzle 38. However, fuel is sucked from chamber 5 to orifice 2 since said orifice is subjected to the strong suction existing in pipe 1 downstream of throttle valve 7.. On the contrary, when this suction decreases substantially, for instance when throttle valve 7 is being opened, the action of spring 47 preponderates and moves piston 42 toward the left of FIG. 5, thus clearing conduit 39 and restarting ejector pump 3.

The operation and the advantages of such means for placing pump 3 out of action as soon as the suction exceeds (in absolute value) a predetermined limit result from the following explanations:

When said means place air pump 36 out of action, the fuel present in conduit 4 is subjected, on the one hand, to a great suction existing in pipe 1 downstream of throttle valve 7 and, on the other hand, to the constant and small suction existing in the portion 1a of air pipe 1. All the liquid that is present at this time at the bottom of chamber 5 is thus drawn to air pipe 1 through orificev 2.

It is known that the amount of fuel introduced under idling running conditions by the'action of pump 36 through orifice 2 must bebelow a given limit to produce acorrect operation. If the means above described did not exist, nozzle 38 should be made very small, more particularly in the case of a multicylinder engine which comprises as many orifices Z and nozzles 38 as there are cylinders. Therefore, the above mentioned means (pipe 37a in the case of FIG. 4 orpiston 42 in the case of FIG. 5) permit of obtaining correct idling running with a nozzle 33 made as great as required for a correct operation of ejector pump 3. a

Finally, the device above described may further include a system for heating the air that is to pass through nozzle 38, in order to avoid icing in venturi 40 due to the expansion of the air delivered through nozzle 38 and/or to evaporation of the fuel in the vicinity of venturi 40. Such a heating system may consist of an electrical resistor or, as shown by FIG. 4, of heat exchanger 49 comprising an inlet 49a and an outlet 49b for a'heating fluid such as the cooling water of the engine. I

According to a modification, the device shown by FIGS. 4.and 5 may also be used in combination with the mechani: cal pump. shown by FIGS. 1 to 3. In other words, the conduit 4 through which fuel flows from chamber 5 to the ejector of FIGS. 4 and 5 may comprise a mechanical pump analogous to that of FIGS. 1 to 3; As a matter oi fact, it has been shown that the ejector device is chiefly efiicient when the mixture that has been metered contains a great amount of air whereas a mechanical pump is chiefly efficient when this mixture contain-s a great amount of liquid. Therefore, the combination of. both permits of obtaining a maximum efficiency in all cases and the comtitration of the two kinds of pump may be useful in some applications of the invention.

The embodiments of FIGS. 6 and 7 comprise the com bination of a feed device such, for instance, as'that of FIG, 5 with a system capable of automatically stopping com pressor 36 when the suction existing in air pipe 1 downstream of throttle valve 7 exceeds (in absolute value) a given limit. i u

If, as shown by FIG. 6, compressor 36 is driven by an electric motor 50 through coupling means 51, this motor being fed with current from a circuit 52, it is possible to arrange the system in such manner that it moves contacts 53 and 54, inserted in said circuit, away from each other when the above mentioned condition exists;

The factor of variation which controls the relative position of contacts 53 and 54 may be the suction existing in air pipe 1, or as shown by FIG. 6 the overpressure existing in delivery conduit 39 upstream of piston 42, provided, of course, that compressor 36 is provided with the usual delivery valve capable of separating from each other compressor 36, when it is stopped, and the conduit 39. For this purpose, this overpressure is transmitted through a conduit 55 to a chamber 56 having one of its walls formed by a diaphragm 57 subjected :to the action of an opposing spring 58, said diaphragm 57 carrying a rod 59 which cooperates with movable contact 54.

According .to the modification of FIG. 7, instead of acting upon the feed circuit of the motor that drives the compressor, the system for stopping said compressor acts upon a clutch interposed between compressor 36 and its source of power. This source of power may be the driving belt 60 of the water pump fan or of the engine dynamo.

This clutch comprises, in the example of FIG. 7, a disc 61 fixed on the shaft 62 of compressor 36 and in frictional contact with the pulley 63 about which belt 66 is passing. Pulley 63 is slidable axially on shaft 62 under the action of a lever 64 pivoting about an axis 65 and provided with fingers 66 engaged in a groove 67 of pulley 63. Lever 64 is actuated by a rod 59a analogous to the rod 59 of FIG. 6, elements 55a, 56a, 57a, 58a and 59a of FIG. 7 being analogous to the elements 55, 56, 57, 58 and 59 of FIG. 6 respectively.

There may be provided in delivery conduit 39 an orifice 68 through which, at least when compressor 36 is out of action, either by being stopped or due to the stopping of conduit 39, air from the outside may be sucked in so as to atomize the fuel passing through venturi 40. Advantageously this orifice 68 is connected with the air intake 13 through a tube 69 branching off from conduit 37. Preferably, orifice 68 is arranged in such manner as to be cleared by piston 42 when this piston is closing conduit 39 (position of FIG. 6) but to be closed by this piston when it clears conduit 39.

The suction pipe 37 of compressor 36 may also be arranged so as to make it possible to connect therewith a conduit 70 coming from the crankcase of the engine fed by the carburetor, as shown by FIG. 6. This conduit 70 opens in the vicinity of the end of tube 69 connected to conduit 37.

The carburetor of FIGS. 6 and 7 works as follows:

When the suction existing in feed pipe 1 is relatively small, compressor 36 is working (contacts 53, 54 of FIG. 6 being applied against each other or the two parts of clutch 61, 63 of FIG. 7 being in engagement) and delivery conduit 33 is cleared by piston 42. Air is then fed under pressure through nozzle 38 and pumps the fuel contained in chamber so that the mixture of air and fuel is injected into pipe 1.

When the suction existing in pipe 1 exceeds (in absolute value) the above indicated limit, diaphragm 44 drives piston 42 toward the right (FIG. 6) and stops delivery conduit 39. Fuel can then be sucked from chamber 5 under the effect of the suction in pipe 1. The pressure existing in conduit 39 upstream of piston 42 rises to a degree such that diaphragm 57 (FIG. 6) or 57a (FIG. 7) is pushed toward the left against the action of spring 58 or 58a. This causes compressor 36 to be stopped, either by the opening of contact 53, 54 (FIG. 6) or by disengagement of clutch 61, 63 (FIG. 7) and thus the power necessary to drive compressor 36 is saved when this compressor is no longer useful, and the wear and tear of this compressor is also reduced.

When compressor 36 is stopped and/ or when piston 42 stops conduit 39, orifice 2 draws not only fuel from chamber 5 but also air from orifice 68. The air entering through this orifice, even in small amount but at very high speed since the suction existing in pipe 1 is great, atomizes the fuel fed through venturi 4% which facilitates its combustion and reduces the consumption of the engine. Orifice 68 is of such cross section area that the air that flows therethrough does not disturb the operation of the engine under idling conditions, this cross section area being as a rule smaller than that of nozzle 38.

As soon as the suction in pipe 1' once more becomes smaller than the above mentioned limit, piston 42 clears conduit 39 and compressor 36 is once more started. Furthermore orifice 68 is closed so that the air delivered by compressor 36 through conduit 39 cannot escape to the outside through this orifice 68.

Finally, when piston 42 stops conduit 39, the suction existing in pipe 1 is transmitted through orifice 68 and tube 69 and sucks in through conduit 70 all the vapors produced in the crankcase. When piston 42 clears conduit 39 and compressor 36 is in operation, the suction conduit 37 of the compressor is subjected to a strong suction which sucks in the vapors from the crankcase through conduit 70, compressor 36 then discharging these vapors into pipe 1 through conduit 39.

In both cases these vapors are introduced into the feed conduit to be admitted therefrom into the engine, where they are burnt.

This arrangement avoids the necessity of evacuating into the atmosphere the vapors from the crankcase which are disagreeable and even noxious. Furthermore, these vapors, which contain a substantial amount of oil in suspension may be used to lubricate at least partly the com pressor.

Of course, the air inlet orifice 68 and the system forintroducing the vapors from the crankcase into the feed conduit may be used in combination with the clutch of FIG. 7. 1 a

To sum up, the invention permits, by making use of a compressor which is working but intermittently, in accordance with the conditions of operation of the engine, of saving motive power and of reducing the wear and tear of the compressor. The invention further permits a better atomizing when the compressor is not to be used and permits by a particularly simple and efficient arrangement, of recycling the vapors from the crankcase.

Of course, the throttling member 8 (FIG. 1) or 9 (FIG. 2) might be substituted for the throttling member 10 of FIGS. 4 and 6.

What I claim is:

1. An internal combustion engine carburetor which comprises, in combination, an air pipe leading to the engine to be fed by the carburetor, a throttle valve in said air pipe, throttling means movably mounted in said air pipe upstream of said throttle valve, so that an air pipe portion is limited between said throttling means and said throttle valve, means responsive to the air pressure difference between the upstream and downstream sides of said throttling means for automatically controlling said throttling means, means fixed with respect to said air pipe forming a fuel chamber, means including a part fixed with respect to said air pipe and a movable part operatively connected with said throttling means, forming a fuel passage opening into said chamber and of a variable cross section area proportional to that of the air passage controlled by said throttling means in said air pipe, means for feeding said fuel passage with fuel under a pressure equal to the air pressure in said air pipe upstream of said throttling means, means forming an injection orifice opening into said air pipe downstream of said throttle valve, a conduit leading from said chamber to said injection orifice, a pump mounted in said conduit to force fuel from. said chamber to said injection orifice and means forming a venting passage between said chamber and said air pipe portion so that the pressure is the same in said chamber and in said pipe portion.

2. A carburetor according to claim 1 wherein the fixed part of said means forming a fuel passage is a tubular wall and the movable part operatively'connected with said throttling means is a needle of a cross section area varying along its length and movable axially with respect to said tubular wall.

3. A carburetor according to claim 1 further comprising means responsive to variations of the suction in said air pipe for placing said pump out of action when said suction exceeds a given limit.

4.. An internal combustion engine carburetor which comprises, in combination, an air pipe leading to the engine to be fed by the carburetor, a throttle valve in said air pipe, throttling means movably mounted in said air pipe upstream of said throttle valve, thus limiting an air pipe portion between said throttling means and said throttle valve, means responsive to the air pressure difference between the upstream and downstream sides of said throttling means for operating said throttling means to keep the air pressure in said air pipe portion substantially constant, means fixed with respect to said air pipe forming a fuel chamber, means including a part fixed with respect to said air pipe and a movable part operatively connected with said throttling means, forming a fuel passage opening into said chamber, and of a variable cross section area proportional to that of the air passage controlled by said throttling means in said air pipe, and means for feeding said fuel passage with fuel under a pressure equal to the air pressure in said air pipe upstream of said throttling means, means forming an injection orifice opening into said air pipe downstream of said throttle valve, a conduit leading from said chamber to said injection orifice, a pump mounted in said conduit to force fuel from said chamber to said injection orifice and means forming a venting passage between said chamber and said air pipe portion so that the pressure is the same in said chamber and in said pipe portion.

5. An internal combustion engine carburetor which comprises, in combination, an air pipe leading to the engine to be fed by the carburetor, a throttle valve in said air pipe, throttling means movably mounted in said air pipe upstream of said throttling valve, so that an air pipe portion is limited between said throttling means and said throttle valve, means responsive to the air pressure difference between the upstream and downstream sides of said throttling means for automatically controlling said throttling means, means fixed with respect to said air pipe forming a fuel chamber, means including a part fixed with respect to said air pipe and a movable part operatively connected with said throttling means forming a fuel passage opening into said chamber and of a variable cross section area proportional to that of the air passage controlled by said throttling means in said air pipe, and means for feeding said fuel passage with fuel under a pressure equal to the air pressure in said air pipe upstream of said throttling means, a conduit leading from said chamber to a point of said pipe downstream of said throttle valve, a venturi at the outlet of said conduit into said air pipe, a nozzle opening at the throat of said venturi for feeding a stream of air, whereby said venturi and said nozzle form an ejector pump to force fuel from said chamber into said air pipe at said point thereof, an auxiliary air pump for supplying said nozzle with an air stream to operate said ejector pump and means forming a venting passage between said chamber and said air pipe portion so that the pressure is the same in said chamber and in said pipe portion.

6. A carburetor according to claim further comprising means responsive to variations of the suction in said air pipe for placing said auxiliary air pump out of action when said suction exceeds a given limit.

7. A carburetor according to claim 5 wherein said auxiliary air pump has its intake located in said air pipe downstream of said throttle valve.

8. A carburetor according to claim 5 further compn's ing an intake conduit leading to said auxiliary air pump and a delivery conduit leading from said auxiliary air pump to said nozzle and valve means responsive to variations of the suction in said air pipe for stopping one of said two last mentioned conduits when said suction exceeds a given limit.

9. A carburetor according to claim 5 further comprising means for heating the air delivered by said auxiliary air pump.

It). A carburetor according to claim 5 further com prising a source of power for normally driving said auxiliary air pump and means responsive to variations of the suction in said air pipe for cutting off said source of power when said suction exceeds a given limit. a

11. A carburetor according to claim 5 further comprises an intake conduit leading to said auxiliary air pump, a delivery conduit leading from said auxiliary air pump to said nozzle, a source of power for normally driving said auxiliary air pump, a valve mounted in said delivery conduit, to control the air circulation therethrough, means responsive to variations of the suction in said air pipe for bringing said Valve into delivery conduit closing position when said suction exceeds a given limit, and means for cutting off said source of power in response to a rise of the pressure in the portion of said delivery conduit upstream of said valve resulting from the fact that said valve is brought into closing position.

12. For use with an internal combustion engine having a crankcase, a carburetor for said engine according to claim 5 further comprising an air intake conduit leading to said auxiliary air pump and a conduit opening into said intake conduit and adapted to be connected with said crankcase.

13. A carburetor according to claim 5 further comprising means responsive to variations of the suction in said air pipe for placing said auxiliary air pump out of action when said suction exceeds a given limit, an intake conduit leading to said auxiliary air pump, a delivery conduit leading from said auxiliary air pump to said nozzle, and an orifice in said delivery conduit communicating with the atmosphere for the inflow of air at least when said auxiliary air pump is brought out of action.

14. For use with an internal combustion engine having a crankcase, a carburetor for said engine according to claim 13 further comprising a conduit in communication with said orifice and adapted to be connected with said crankcase.

References Cited by the Examiner UNITED STATES PATENTS 1,273,356 7/18 Good 26l149 1,402,749 1/22 Du Pont 261-50 2,261,490 11/41 Weber 26l50 2,777,678 1/57 Udale Q61-50 2,863,433 12/58 Sarto 123139 2,968,473 1/61 Mick 261-78 3,005,625 10/61 Holley 26l69 3,034,771 5/62 Harris 26l36 OTHER REFERENCES Huber: German printed application No. 1,082,456, 5/60.

HARRY B. THORNTON, Primary Examiner. HERBERT L. MARTIN, Examiner. 

1. AN INTERNAL COMBUSTION ENGINE CARBURETOR WHICH COMPRISES, IN COMBINATION, AN AIR PIPE LEADING TO THE ENGINE TO BE FED BY THE CARBURETOR, A THROTTLE VALVE IN SAID AIR PIPE, THROTTLING MEANS MOVABLY MOUNTED IN SAID AIR PIPE UPSTREAM OF SAID THROTTLE VALVE, SO THAT AN AIR PIPE PORTION IS LIMITED BETWEEN SAID THROTTLING MEANS AND SAID THROTTLE VALVE, MEANS RESPONSIVE TO THE AIR PRESSURE DIFFERENCE BETWEEN THE UPSTREAM AND DOWNSTREAM SIDES OF SAID THROTTLING MEANS FOR AUTOMATICALLY CONTROLLING SAID THROTTLING MEANS, MEANS FIXED WITH RESPECT TO SAID AIR PIPE FORMING A FUEL CHAMBER, MEANS INCLUDING A PART FIXED WITH RESPECT TO SAID AIR PIPE AND A MOVABLE PART OPERATIVELY CONNECTED WITH SAID THROTTLING MEANS, FORMING A FUEL PASSAGE OPENING INTO SAID CHAMBER AND OF A VARIABLE CROSS SECTION AREA PROPORTIONAL TO THAT OF THE AIR PASSAGE CONTROLLED BY SAID THROTTLING MEANS IN SAID AIR PIPE, MEANS FOR FEEDING SAID FUEL PASSAGE WITH FUEL UNDER A PRESSURE EQUAL TO THE AIR PRESSURE IN SAID AIR PILE UNSTREAM OF SAID THROTTLING MEANS, MEANS FORMING AN INJECTION ORIFICE OPENING INTO SAID AIR PIPE DOWNSTREAM OF SAID THROTTLE VALVE, A CONDUIT LEADING FROM SAID CHAMBER TO SAID INJECTION ORIFICE, A PUMP MOUNTED IN SAID CONDUIT TO FORCE FUEL FROM SAID CHAMBER TO SAID INJECTION ORIFICE AND MEANS FORMING A VENTING PASSAGE BETWEEN SAID CHAMBER AND SAID AIR PIPE PORTION SO THAT THE PRESSURE IS THE SAME IS SAID CHAMBER AND IN SAID PIPE PORTION. 